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831.
Qingyun Chen Ying Xi Yuezhen Bin Masaru Matsuo 《Journal of Polymer Science.Polymer Physics》2008,46(4):359-369
Carbon fiber (CF) filled low‐molecular‐weight polyethylene (LMWPE) and ultra‐high molecular weight polyethylene (UHMWPE) composites were prepared by the gelation from solution and the kneading in the melting state. The content of carbon fibers was fixed to be 23.5 vol %. The resistivity, positive temperature coefficient (PTC), and dielectric behaviors of the composites became more pronounced with increasing content of LMWPE with much higher thermal expansion than that of UHMWPE. The PTC effect became most significant, when the blend ratio of LMWPE to UHMWPE was 9/1. Beyond 9/1, the PTC effect was less pronounced. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the UHMWPE and LMWPE chains within the composite crystallized independently by gelation from solution and were virtually unaffected by the presence of carbon fibers. Consequently, it was confirmed that carbon fibers selectively were localized in the mixed region of LMWPE and UHMWPE for the composite (3/1 and 6/1) and mainly in the region of LMWPE for the 9/1, 12/1, and 15/1 composites. This indicated that the content of carbon fibers within LMWPE region was the highest for the 9/1 composite and the 9/1 composite provides the most significant PTC effect. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 359–369, 2008 相似文献
832.
The copper phthalocyanine (CuPc) oligomer with high dielectric constant was synthesized by the solution method. The FT‐IR and X‐ray diffraction results revealed its chemical structure. The high dielectric constant of CuPc was proved to result from the free movement of charge carriers along the conjugated orbitals. The composites of CuPc and sulfonated polyurethane (PUI) were prepared and the contents of CuPc in the composites were varied from 10 to 50 wt %. The dielectric performance was greatly enhanced for the composite compared with that of average polymers. Different from the behaviors appeared in a common composite with conductive fillers, there is no percolation phenomenon observed in the CuPc/PUI composite, and the dielectric constants of CuPc/PUI composites decreased with the increase in the CuPc content, which is assumed to due to the strong electrostatic interactions between CuPc and PUI. Considering the many‐body interactions within the bulk sample and the contact effect between the bulk sample and the metallic electrode, an equivalent circuit was established to simulate the dielectric behaviors of the composites and computational curve fitting was done. The results were in good agreement, indicating that the dielectric responses of the composites come from both the extrinsic and the intrinsic contributions. The extrinsic was associated with the Maxwell‐Wagner relaxation at the interface between the electrode and the bulk sample, and the intrinsic was associated with the huge dipoles provided by the mobile charges within the CuPc grains and the interaction among them in the bulk composites. A circuit model concerning the universal dielectric response was proposed in describing the intrinsic contribution, which quantitatively verified the strong interaction among the dipoles with the relaxation time, representing the aggregated structure of CuPc when its content was high in the composites. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1146–1155, 2009 相似文献
833.
Koichiro Sakaguchi Shunsuke Furukawa Satoshi Matsuo Naotaka Sakashita Takushige Katsura Kyoko Yamazaki Hideo Kawaguchi Atsushi Maki Eiji Okada 《Optical Review》2009,16(2):74-80
The simplified cranial window, which is transparent thinned skull, has been used for the optical imaging of cortical tissue
of small animals to measure the concentration change in haemoglobin as an intrinsic signal of brain activation. The multi-spectral
images of the cortical tissue of guinea pigs through the skull cranial window were compared with those of the exposed cortex
to evaluate the influence of the scattering and absorption properties of the skull on the measurement of the concentration
change in haemoglobin. Although skull thickness affects the sensitivity of the optical signal due to a decrease in mean optical
path length in the cortical tissue, the influence of the skull cranial window on the wavelength dependence of optical path
length can be ignored when the skull thickness is less than approximately 100 mm. Accurate concentration changes in oxygenated
and deoxygenated haemoglobins can be calculated from the optical signal measured through a skull cranial window and the wavelength
dependence of optical path length for the exposed cortex. 相似文献
834.
Shigemasa Matsuo Kanoko Furuta Toshiyuki Fujii Katsuhiko Nagai Noriyuki Hatakenaka 《Solid State Sciences》2009,11(5):942-944
A simple scheme for controlling the gate operation for qubit–qubit interactions in superconducting phase qubits using a moving fluxon is proposed. The basic unit of our scheme is composed of three capacitively coupled flux-biased phase qubits. One of the qubits acts as a switch connecting the other two (two logical qubits) with an identical energy separation. The fluxon controls the energy separation of the switch qubit via its inductive coupling, leading to the resonance among qubits appropriately adjusting the fluxon velocity. As a result, the resonance is capable of performing a gate operation between two logical qubits. In addition, we show that this provides a simple scheme for generating entangled states of many qubits in solid-state quantum nanocircuits. 相似文献
835.
A series of 1,1-dimethyl-4,5:8,9-dibenzo-1-silacycloundeca-4,8-diene-2,6,10-triyne (DST)-substituted phenyleneethynylenes were successfully synthesized by reaction of Me2SiCl2 with dimagnesium dianions which had been prepared from 2,2′-diethynyl(diphenylethyne) derivatives by treatment with 2 equiv of MeMgBr. All the products were white-to-pale yellow powder stable enough to handle in the air, and their photoluminescence spectra were recorded both in solution and in solid state. 相似文献
836.
Mugio Nishizawa Tomoaki Iyenaga Hirofumi Yamamoto Kosuke Namba Yoshikazu Shizuri Yoshihide Matsuo 《Tetrahedron letters》2007,48(24):4229-4233
Total synthesis of (±)-thallusin was achieved using Hg(OTf)2·PhNMe2-induced olefin cyclization, and Suzuki coupling with a pyridylboronic acid derivative. Hg(OTf)2 also acted as a catalyst to isomerize the double bond into the more thermodynamically stable isomer when treated in toluene. Synthetic (±)-thallusin as well as an analogue showed morphogenesis-inducing activity. 相似文献
837.
A micro glucose sensor consisting of an interdigitated array gold microelectrode was developed. The interdigitated array structure, which has 10 microns band width and 10 microns band gap, was fabricated in a small region (2.5 x 5 mm2) on a quartz substrate. Glucose oxidase was chemically fixed onto the electrode surface through self-assembled monolayer of 11-mercaptoundecanoic acid; ferroceneacetic acid was used as electron mediator. Electrochemical properties of the glucose oxidase-immobilized microelectrode were investigated by cyclic voltammogram measurements. Results confirmed that the reductive ferroceneacetic acid generated at counter electrode diffuses through a narrow band gap (10 microns) and can reach the working electrode surface. 相似文献
838.
New conservative finite difference schemes for certain classes of nonlinear wave equations are proposed. The key tool there is “discrete variational derivative”, by which discrete conservation property is realized. A similar approach for the target equations was recently proposed by Furihata, but in this paper a different approach is explored, where the target equations are first transformed to the equivalent system representations which are more natural forms to see conservation properties. Applications for the nonlinear Klein–Gordon equation and the so-called “good” Boussinesq equation are presented. Numerical examples reveal the good performance of the new schemes. 相似文献
839.
The vertical distribution of iron species in the sediments collected from Kuhai Lake was investigated in this study. Their Mössbauer spectra were composed of one sextet and four doublets ascribable to one paramagnetic high-spin Fe3+, two paramagnetic high-spin Fe2+ with different quadrupole splittings, and one diamagnetic low-spin Fe2+ that corresponds to pyrite (FeS2). The distribution of pyrite was considered to reflect the climatic change during the past 2,000 years. Mössbauer spectroscopy was successfully applied to the analysis of the Kuhai Lake sediments so as to reconstruct the history of the past climate. 相似文献
840.
M. Mazilu S. Juodkazis T. Ebisui S. Matsuo H. Misawa 《Applied Physics A: Materials Science & Processing》2007,86(2):197-200
The presence of dislocations has been revealed by numerical processing of high–resolution transmission electron microscopy images from the regions affected by a shock wave propagation. The shock wave was triggered by a single 220 fs duration pulse of 30 nJ at an 800 nm wavelength inside sapphire at approximately 10 μm depth. The shock-amorphised sapphire has a distinct boundary with the crystalline phase, which is not wet etchable even at a dislocation density of ≃8×1012 cm-2. PACS 81.07.-b; 96.50.Fm; 62.50.+p; 47.40.Nm; 81.40.-z 相似文献